On February 8, 1841, Duke Wilhelm married Princess Theodelinda de Beauharnais (1814-1857), the daughter of Eugène de Beauharnais, Duke of Leuchtenberg. Four daughters were born from this marriage:

• Princess Augusta Eugenie of Urach (1842-1916). Married first Count Rudolf von Enzenberg zum Freyen und Jochelsthurn (1835-1874) and second Count Franz von Thun und Hohenstein (1826-1888).
• Princess Marie Josephine of Urach (1844-1864).
• Princess Eugenia Amalie of Urach (1848-1867).
• Princess Mathilde of Urach (1854-1907). Married Paolo Altieri, Prince of Viano.

On February 15, 1863, he married Princess Florestine of Monaco (22 October 1833 France - 4 April 1897 Stuttgart) , daughter of Florestan I, Prince of Monaco, and they had two sons:

• Wilhelm, 2nd Duke of Urach (1864-1929), later King Mindaugas II of Lithuania.
• Prince Karl of Urach (15 February 1865 - 5 December 1925).

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